White, Mary Anne
Recent Submissions
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High-resolution, high-sensitive ac calorimeter.
A high-resoln., high-sensitivity, automated ac calorimeter capable of heat capacity measurements of very small samples (m < 20 mg) with a temp. resoln. of a few mK in the ac mode is described. This calorimeter also can be ... -
Automated, small sample-size adiabatic calorimeter.
An automated adiabatic calorimeter is described with an internal vol. of 5 cm3, operable at 30-380 K. One of the main advantages of this calorimeter over others in use is the shorter down time during sample changes, due ... -
X-ray absorption spectroscopy studies of local structure and electronic properties of NaxSi136 (0 < x < 24) clathrates
We have probed both the local structure and the electronic properties of Na-containing type II Si clathrates by x-ray absorption spectroscopy. The near-edge region of the spectrum is particularly sensitive to the local ... -
Structure, thermal, and transport properties of the clathrates Sr8Zn8Ge38, Sr8Ga16Ge30, and Ba8Ga16Si30
The structural parameters, thermal properties, and transport properties of three type I clathrates, namely Sr8Zn8Ge38, Sr8Ga16Ge30, and Ba8Ga16Si30, have been determined at or below room temperature. The structural ... -
Thermal and lattice dynamical properties of Na8Si46 clathrate
The experimental heat capacity of Na8Si46 has been determined from 35-300 K, and its lattice parameters have been measured over the range 100-330 K. The experimental heat capacity and the thermal-expansion coefficient ... -
Heat capacity of gadolinium near the Curie temperature.
High-resoln. ac calorimetric data near the Curie point are reported for several single crystals of gadolinium. The crit. temp. and the shape of the heat-capacity curve near Tc both depend on the sample-prepn. procedure, ... -
Spin waves and quantum criticality in the frustrated XY pyrochlore antiferromagnet Er2Ti2O7
We report detailed measurements of the low temperature magnetic phase diagram of Er2Ti2O7. Heat capacity and time- of- flight neutron scattering studies of single crystals reveal unconventional low- energy states. Er3+ ... -
Structural principles and amorphouslike thermal conductivity of Na-doped Si clathrates
The postulated low thermal conductivity and the possibility of altering the electronic conductivity of metal-doped clathrates with semiconducting host elements have stimulated great interest in exploring these compounds ... -
A thermodynamic investigation of dynamical disorder in phase II of CBr4.
CBr4 is an archetypal example of a pseudospherical mol. that can form an orientationally disordered phase (phase I, 320 K < T < 365 K). At lower temps., phase II is the stable phase; although it must be more ordered than ... -
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Apparatus for dynamical thermal measurements of low-thermal diffusivity particulate materials at subambient temperatures
Apparatus for measurement of thermal diffusivity of particulate matter in the temperature range of 10-300 K is described. The basis of the measurement is modulated radial heat flow into a cylindrical sample, with a relatively ... -
Transport properties of Na8Si46
We report on transport properties of polycrystalline Na8Si46 in the temperature range 10 to 300 K. The compound is a type I clathrate with Na incorporated into polyhedra formed by framework Si atoms. Seebeck coefficient ... -
Thermal and Diffraction Studies of Phase-Transitions in the Incommensurate Compound [P(Ch3)(4)]2CuCl4
Calorimetric and x-ray-diffraction studies of the commensurate -
Technique for determination of accurate heat capacities of volatile, powdered, or air-sensitive samples using relaxation calorimetry
We introduce a four-step technique for the accurate determination of the heat capacity of volatile or air-sensitive samples using relaxation calorimetry. The samples are encapsulated in a hermetically sealed differential ... -
Heat capacity, lattice dynamics, and thermodynamic stability of the negative thermal expansion material HfMo2O8
We explore the lattice dynamics of the negative thermal expansion material, cubic HfMo2O8, through analysis of its heat capacity (measured from 0.5 to 300 K) and its room-temperature Raman spectrum. Its heat capacity is ... -
Low thermal conductivity of the negative thermal expansion material, HfMo2O8
The thermal conductivity of the cubic polymorph of hafnium molybdate, HfMo2O8, was determined over the temperature range of 2-400 K. The values of thermal conductivity were low (0.64 +/- 0.15 W m(-1) K-1 at T=300 K for a ... -
Photoacoustic Investigation of the Temperature and Magnetic-Field Dependence of the Specific-Heat Capacity and Thermal-Conductivity Near the Curie-Point of Gadolinium
The photoacoustic technique was used as a simple but accurate tool to simultaneously determine the specific-heat capacity C and thermal conductivity kappa of gadolinium in the neighborhood of the Curie point. One ...
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